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Selecting a Dynamometer

Magtrol Dynamometers cover a wide range of Torque, Speed and Mechanical Power ratings. To select the appropriate size Dynamometer for your motor testing needs, you will need to determine the Maximum Torque, Speed and Power applied to the Dynamometer:
 
Maximum Torque
It is important to consider all torque points that are to be tested, not only rated torque, but also Locked Rotor and Breakdown Torque. Dynamometer selection should initially be based on the maximum torque requirement, subject to determining the maximum power requirements.
 
Maximum Speed
This rating is to be considered independent of torque and power requirements, and is the maximum speed at which the Dynamometer can be safely run under free run or lightly loaded conditions. It is not to be considered as the maximum speed at which full braking torque can be applied.
 
Maximum Power Ratings
These ratings represent the maximum capability of the Dynamometer Braking System to absorb and dissipate heat generated when applying a braking load to the motor under test. The power absorbed and the heat generated by the Dynamometer is a function of the Torque (T) applied to the motor under test, and the resulting speed (n) of the motor. This is expressed in these power (P) formulas:
SI: P (watts) = T (N·m) × n (rpm) × (1.047 × 10-1)
English: P (watts) = T (lb·in) × n (rpm) × (1.183 × 10-2)
Metric: P (watts) = T (kg·cm) × n (rpm) × (1.027 × 10-2)
All of Magtrol's controllers, readouts and software calculate horsepower
as defined by 1 hp = 550 lb·ft / s. Using this definition:
hp = P (watts) / 745.7

To calculate power, use Magtrol's online motor power calculator

The Dynamometer's ability to dissipate heat is a function of how long a load will be applied. For this reason, the Maximum Power ratings given are based on continuous operation under load, as well as a maximum of 5 minutes under load.
To safely dissipate heat and avoid Dynamometer failure, the maximum power rating
is the most important consideration in selecting a Dynamometer.
 
Magtrol, Inc (USA): 716-668-5555 • magtrol@magtrol.com ~ Magtrol SA (Switzerland): 41 (0)26 407 3000 • magtrol@magtrol.ch
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